Since thienamycin having useful activities as an antibiotic was discovered, a number of carbapenem derivatives have been synthesized and applied for patents. For example, EP 160,391 (The term "EP" as used herein means an "European patent publication") proposes various alicyclic aminothio groups for the side chain at the 2-position of the carbapenem skeleton. EP 160,391 includes a generalized and categorical statement about alicyclic aminothio groups but as far as can be inferred from the working examples included therein, the technology is directed simply to carbapenem compounds having a 3-pyrrolidinylthio group N-substituted with a substituted imidoyl group or 5-(3,4,5,6-tetrahyiropyrimidinyl)thio group at the 2-position of the carbapenem skeleton. Furthermore, notwithstanding the statement that these carbapenem compounds in general have excellent antibacterial activity, this assertion is not supported by factual antibacterial activity data at all. Particularly, although this literature includes an extensive listing of 122 compounds, only 11 different side chain groups can be identified from the compounds allegedly synthesized in the working examples.
While carbapenem derivatives are useful for the treatment of human and animal diseases caused by pathogenic bacteria, antibacterial activities of the state-of-the-art carbapenem derivatives are not sufficiently satisfactory, and there has been a demand to develop a compound exhibiting excellent antibacterial activity against various pathogenic bacteria.
Imipenem, a carbapenem compound now clinically used, is decomposed by renal dehydropeptidase (hereinafter abbreviated as DHP) similarly to thienamycin, so that it is used in combination with a DHP inhibitor, e.g., cilastatin. Hence, a carbapenem compound having improved stability against DHP as well as satisfactory antibacterial activity has been demanded.